Comparative Analysis of Simplified and Extended Chemistry Models in Low-Pressure Argon DC Discharge

In the present work, a comparative study of the influence of plasma-chemical reactions on the results of fluid modeling of a direct current (DC) glow discharge in argon at a pressure of 1 Torr is presented. Here two approaches are compared: a Simplified Chemistry Model (SCM), which accounts for only one lumped excited level, and an Extended Chemistry Model (ECM), in which metastable and resonance states are explicitly separated, and resonance radiation transport is taken into account. The use of SCM leads to an overestimation of plasma density (by a factor of 2-3) and discharge current (by ~23%) compared to the more detailed ECM. It is shown that neglecting radiative losses from resonance levels in simplified models violates the energy and particle balance, leading to inaccurate predictions even at low pressures. Analysis of ionization rates demonstrates that the simplified model artificially overestimates the contribution of stepwise ionization. The results demonstrate the necessity of accounting for the detailed structure of excited levels for quantitatively accurate modeling of gas discharge devices even at low pressures.